client server and exchange of messages over internet

I want to create a simple client server c++ application for exchange of messages over internet
I have written a client server using TCP,sockets and is working perfectly on Internet . But the thing is I manually have to open the router ports... that is I have to configure router my self.
Could you please guide me what should I look for so that my code can work for intenret without manually opening ports.
We use several messengers, we nerver have to manually open the port so how they operate.
The client server code is very simple and basic.
I heard about UPnP and hole punching.
Reverse port tunneling. Would it help.??

And I am developing it on Linux.
Please I will appreciate your help and if you can give me a sample of code. I am a novice in network programing
Regards

> Could you please guide me what should I look for so that my code can work for intenret without manually opening ports.

Not possible sorry. The whole point of firewalls is that they block unwanted traffic, and that's why they allow you to open ports; this lets you define what is wanted.

The only thing you can do is to change your code so that it works over ports that you can expect to be open. For example port 80 (http) is often open so if you code up your packets to work over HTML then you can fairly reliably get through most firewalls.

> Could you please guide me what should I look for so that my code can work for intenret without manually opening ports.

Not possible sorry. The whole point of firewalls is that they block unwanted traffic, and that's why they allow you to open ports; this lets you define what is wanted.

The only thing you can do is to change your code so that it works over ports that you can expect to be open. For example port 80 (http) is often open so if you code up your packets to work over HTML then you can fairly reliably get through most firewalls.

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Thanks a lot for your reply.. I am using sockets and i tried using port 80 and other well known ports. The error i got is can not bind socket..(some thing like that)
so i guess i cant use port already in use..
There are some P2P clients then how do they communicate with peers. they I guess don't use these well known ports.. Or is it so. that P2P instead of the name Peer to peer still use servers